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Gray skies over Waikoloa looking up to Mauna Loa, where Winter Storm Warnings are up today. Photograph: Weatherboy

The National Weather Service office in Honolulu, Hawaii continues Winter Storm Warnings for the higher elevations of the Big Island of Hawaii today as a Kona Low moves through the Aloha State.

A Kona Low is a storm more typical of the winter weather season in the Pacific and is formed with winds coming from a westerly direction. In the Hawaiian language, “Kona” typically refers to the western side of the Island. (It is also the name for Hawaii Island’s largest city on the western side, Kona.) These cold-core, extratropical cyclones often bring numerous days of hazardous weather to the entire island state. Hazards can include extremely heavy tropical downpours which cause flash floods, landslides, rockslides, and mudslides. Other hazards include large hail, damaging wind gusts, and rough, potentially destructive surf.

Kona Lows also produce something that Hawaii isn’t generally known for: heavy snow. While images of palm trees and poolside cocktails with umbrellas are the first thoughts that come to mind about outdoor life in Hawaii, the state’s highest elevations often will get snow in the winter months. Kona Lows produce some of the heaviest snows in Hawaii.

This week’s Kona Low is no exception to the heavy snow: 6″ or more is expected on the Big Island summits and upper slopes today. In addition to heavy snow, damaging winds in excess of hurricane force are expected; the National Weather Service warns that southwest to west winds of 55-65mph are likely with gusts over 75mph. In past Kona Low storm systems, winds have exceeded 100mph. Heavy snow with strong winds will lead to poor visibility below 1/4 mile. Due to the severe winter weather, the Mauna Kea Summit road has been closed by local officials today.

A potent storm system will bring blizzard conditions to a large part of the northeast; heavy snow will also fall over a large area from late Monday through early Wednesday.

A crippling blizzard will impact the northeast later Monday into Tuesday before wrapping up early Wednesday morning. While heavy snow will fall out of the sky onto many, coastal areas will be impacted by damaging winds, significant high wave action, coastal flooding, and major beach erosion.

High pressure will continue to build into the northeast today, allowing clear skies for much of the region tonight. Some mid-level clouds will begin to move into the northeast late tonight, spilling over from an approaching flat upper ridge. With recent snow covering the terrain over central and northern Pennsylvania and New Jersey, New York, and southeastern New England, along with diminishing winds, temperatures will drop significantly tonight. Expect partly to mostly cloudy skies from New York City and points north and west by tomorrow morning as the flow across the eastern two thirds of the continental US begins to amplify.

Powerful wind gusts will create their own set of problems in the northeast as the storm pushes up the coast, as illustrated in this graphic from the National Weather Service.

Later on Monday, clouds will begin to stream from the south to the north as a developing coastal storm takes shape off the US east coast. Energy arriving from the Pacific Ocean into the Northwestern US this morning will dive into the southern US, eventually phasing with subtropical energy Monday night. This phased energy will track up the coast around digging northern stream energy that’ll take the shape of a developing upper low by the Great Lakes by Tuesday. These systems will eventually phase together as a closed low over the northeastern US Tuesday night into early Wednesday. At the surface, this upper-level scenario will allow for low pressure to develop across the US southeast Monday. This low will intensify as it tracks north towards the Carolina coast Monday evening. It will eventually pass northeast between Montauk Point on Long Island and 40 degrees latitude / 70 degrees longitude known as the “benchmark” area for major northeast storms. By Tuesday evening, this storm will be near Cape Cod as a low pressure system with pressure readings as low as the low 980mbs.

Since last night, computer guidance that meteorologists use to aid in their forecasting has shifted the storm path and structure a bit. These shifts will keep the rain/snow line from moving too far north, while also bringing the heaviest precipitation closest to the coast. The exception to this will be over far eastern Long Island, Block Island, Martha’s Vineyard, Nantucket, and Cape Cod, where mixing with sleet and/or rain will be possible at times as the storm winds up the coast. As such, snowfall accumulations there will be somewhat lower.

In terms of a heavy snowfall, coupled jet structure, approaching mid level shortwave energy, and strong frontogenetic forcing, all interacting with a significant inflow of gulf and sub-tropical moisture, will yield to very heavy snow. In parts of New Jersey and the New York City metro area, there could be some extreme heavy snowfall rates in excess of 2.5″/hour late Monday night through Tuesday afternoon.

Thunder snowstorms will form, leading to isolated bands and cells of extremely heavy snow. As these areas of intense snowfall develop, they will rob nearby areas of moisture. As such, we expect heavy snow pockets to be speckled with areas of lighter amounts around them. Remember: when thunder roars, head indoors! Lightning can kill in any season.

In addition to the shift in storm path and structure is the forward speed of this storm. This storm will be moving along somewhat faster than earlier thought. Because of the speed of the system, it won’t be able to linger around to drop historic amounts of snow. Nevertheless, snowfall will be heavy and crippling for many.

Coastal flooding is likely from the upcoming storm. As this chart from the National Weather Service shows for Atlantic City, NJ, moderate flooding and blow-out tides are possible during the storm.

Heavy snow will continue through much of the day Tuesday before wrapping up during the evening hours. A “dry-slot” will be associated with this storm and will aid in shutting off the snowfall. A dry-slot is zone of dry air which wraps east or northeastwards into the southern and eastern parts of a synoptic scale or mesoscale low pressure system and is responsible for creating the comma-like shape of a mature storm on satellite imagery. We will be tracking this development which will also have a negative impact on snowfall amounts. While the dry-slot will lead to diminished snowfall amounts, the area just north of it, nick-named the “comma-head”, will see some of the heaviest snowfall rates and amounts.

While the storm exits the northeast later Tuesday and early Wednesday, snow shower activity will persist for many on the day on Wednesday as winds howl from the northwest. These snow showers may leave additional light accumulations throughout the northeast then.

While northwest winds will howl on Wednesday, they will really roar on Tuesday as the storm system takes shape along the east coast. Wind gusts may approach 30mph as far inland as the Delaware/Maryland border and eastern Pennsylvania near Philadelphia. 40mph wind gusts are likely along and east of the Garden State Parkway in New Jersey and across all of Long Island. 40mph+ wind gusts will also be felt across much of Connecticut, Massachusetts, Rhode Island, eastern New Hampshire, and coastal Maine. Across southeastern New England, especially from south of Boston to Block Island, some wind gusts may exceed 50mph.

These winds will topple tree limbs and utility wires, possibly leading to long-duration power outages. There could also be minor structural damage, especially on exposed coastal areas. Everyone, coast and well inland, should secure any outdoor objects that may blow around in gusty winds during the storm. It is these winds that will also create blizzard conditions.

While most people associate a large snow storm with the word “blizzard”, that is meteorologically incorrect. Blizzards are defined by their winds and visibility; it is even possible to have a blizzard without any fresh snow falling. To meet blizzard criteria, bad weather conditions need to persist for more than 3 hours: namely, winds need to be at 35mph or more and visibility due to either fresh falling snow or blowing fallen snow needs to be reduced down to a quarter mile or less.

You don’t need to have blizzard conditions to have dangerous snow storm conditions. Blowing snow is wind-driven snow that reduces visibility. Blowing snow may be falling snow or it could be snow on the ground that is picked up by the wind. Snow flurries are typically defined as light snow falling for short duration with little to no accumulation while snow showers are known for snowfall at varying intensity for brief periods of time with light accumulations. Snow squalls, however, are severe, brief, intense snow showers accompanied by strong, gusty winds, and while short-lived, snow squalls can produce quick and significant accumulations. In and after snow storms, snow squalls can threaten a region with additional hazards.

The heavy snow and strongest winds should begin to wind down from southwest to northeast late Tuesday into early Wednesday as the low pressure pulls east of New England. But with snow showers and gusty northwest winds lingering into Wednesday as the phased upper low moves through, visibility may drop again from time to time in blowing snow.

In addition to a damaging wind threat, there is also the threat of significant coastal flooding, especially along the Jersey Shore, the south shore of Long Island, and southeastern New England. Some flooding could be moderate, especially at times of high tide on Tuesday. If you are in a low lying coastal area prone to coastal flooding, take appropriate steps now to protect life and property. As the storm pulls away, there is also a risk of blow-out tides, especially in the back bays of the Jersey Shore.

High and rough surf will also batter beaches leading to significant beach erosion.

Eventually high pressure will build back into the northeast later Wednesday, with fair and dry weather arriving for Thursday.

A potent storm system will impact the northeast. The storm may hug the coast or may head more off-shore; each possibility brings major changes to possible snowfall amounts. It is still too soon to say how this storm will evolve as it moves towards the northeast on Tuesday.

A major winter storm will pound the northeastern United States on Tuesday, dropping very heavy snow and whipping the coastline with damaging winds and rough surf. While Sunday and Monday will be tranquil in the northeast, it will be very cold with highs forecast to be about 15-25 degrees below normal. Meanwhile, the ingredients will be coming together for a significant storm to form off the North Carolina coast by Monday afternoon.

This storm will rapidly intensify and go through a process called bombogenesis. Bombogenesis is defined as a mid-latitude cyclone that drops in surface barometric pressure by 24 or more millibars in a 24-hour period. With an abundant moisture supply, great support from upper layers of the atmosphere, and a set-up that’s ripe for rapid development, a major Nor’easter will blossom and move up the northeast coastline late Monday evening into Tuesday. By Wednesday morning, the low pressure center should be near eastern Maine, bringing trouble to the Canadian Maritimes while the US begins the big dig-out.

Meteorologists making forecasts are aided by computer forecast models that digest large volumes of data and spit out robust data sets profiling different layers of the atmosphere; two of the most popular global models are the American (GFS) and European (ECMWF.) They each have their strengths and weaknesses, although this winter the European model has generally performed better than its American counterpart with big storms.

While we’re less than 4 days away from the storm, there’s still decent disagreement between these models and their opinions they render. The American model appears to be a western outlier, bringing a track of the primary low pressure system very close, if not a hair inland, over the coast. The European model shows a track further out to sea. A track closer to the shore line would produce much more precipitation, but it would also increase the odds of a a more northern rain/snow line that would cut snow amounts down due to non-snow such as sleet and rain falling. A track more offshore would keep cold air in place, bringing up snow totals along the coast. Tracks far off shore could also keep most of the available moisture to work with off-shore as well. At this time, the National Weather Service’s Weather Prediction Center believes a blend of those solutions will occur.

At this time, Weatherboy believes it is too early to commit to a forecast path. Beyond the complexity of the future track is the future structure of this system. Because this overall system is really the sum of many parts and it is not yet completely understood how Mother Nature will assemble those parts, there is no early, crystal-clear solution as there have been with past major storms such as the March Superstorm of 1993 and the Boxing Day Blizzard of 2010. In those storms, the pattern and available track for those storms to pursue was understood and “locked-in” several days before the storms impacted the northeast. Unfortunately, the same just isn’t true yet for this system.

There are two probable paths for the storm to pursue: hug the coast or head off-shore. In our snow maps here, we’ve illustrated how those very different paths would lay down very different snow amounts across the northeast. The coastal hugger would bring the threat of rain, sleet, or a mix of rain/sleet/snow up into New Jersey, keeping snow totals low along and south of I-95 in the Garden State south into Delaware and Maryland. But a coastal hugger would also slug more moisture inland, bringing 1-2′ snow to portions of Pennsylvania and New England. The off-shore track would pull the impacts of the storm further east, bringing the heaviest snow to portions of central New Jersey and southeastern New England. If the storm were to head even further off-shore, that heavy snow would go with it. While a well off-shore solution would eliminate change-over or mixing chances with rain or sleet, it would also cut snowfall amounts dramatically as you move away from the coast.

More data needs to be analyzed before confidence is increased in the forecast specifics, especially as it relates to snow. That confidence may not rise until Sunday afternoon. In the meantime, the National Hurricane Center has confirmed that Reconnaissance Aircraft typically used to investigate hurricanes have been deployed to this developing system to sample the atmosphere. These samples and assorted readings throughout their journey in the atmosphere will provide us with a greater level of detail of the set-up that’ll eventually impact the track and intensity of this storm.

Regardless of the storm track, the northeast will be hit by typical harsh Nor’Easter conditions: damaging wind gusts, coastal flooding, and beach erosion are all possible from the Delaware Beaches up the Jersey Shore to the South Shore of Long Island to Nantucket, Martha’s Vineyard, Cape Cod, and Block Island. While confidence is low with snow accumulation specifics, confidence is moderately high that there will be severe winds at the coast. The prime period for damaging winds would be from early Tuesday morning through Tuesday afternoon along the northeast. The best chance of coastal flooding will be during times of high tide on Tuesday.

By Wednesday, the low should quickly pull away. While the storm heads into the Canadian Maritimes, there could be lingering snow showers throughout the day, especially over northeastern Pennsylvania, northwestern New Jersey, and the higher terrain of New England. High pressure will build in during the day on Wednesday with another storm threat arriving later Thursday.

A complex, volatile weather pattern will produce a significant winter storm followed by a dramatic warm-up in the eastern United States.

In the short-term, Old Man Winter will be dominating the pattern and the news over the next week. Three distinct systems will bring snow to an area that hasn’t seen much of it this winter.

The first system, known as a clipper system, will drop light snow across northern Pennsylvania, New Jersey, the New York City metro area, and southern New England on Friday.

The second system will drop much further south, bringing snow to portions of Tennessee, North Carolina, and southern Virginia.

The third but likely to be largest of the storms could bring very heavy snow to portions of the I-95 corridor from Philadelphia to Boston, with the heaviest snow possible over the northern half of New Jersey, northeastern Pennsylvania, the New York City metro region, Connecticut, Rhode Island, and southeastern Massachusetts.

BSR forecasting tool shows a ridge over the middle of the country while New England is susceptible to back door cold fronts Credit: OrganicForecasting.com

Joseph Renken, founder of the Bering Sea Rule (BSR) said, “When we look at what happened in the Bering Sea from about February 22nd into early March, a huge ridge dominated the region and was centered over the International Date Line (IDL) for those 10 days or so. That tells us a ridge will develop over the United States mid to late next week and will last well into late March. In our research, we have found that the IDL teleconnects to a line found from New Orleans stretching due north to the Canadian border. Thus, the ridge should be centered in that approximate region.”

Warm weather develops under a ridge as the jet stream is pushed well to the north while abundant sunshine warms the land. Temperature departures will be very positive as the ridge takes hold and strengthens. That sets up an interesting battleground in the Northeast, especially in New England, as we see a clash between winter and spring. Much below average temperatures will be the rule in New England the next week or so. Right behind this Arctic air, though, temperatures will rebound to much above average reading in a matter of a few days.

Canadian government forecast for probability of temperature anomalies between the 15th and 22nd of March. Credit: Environment Canada

“It now seems like after the third and final snow threat early to middle part of next week, warm air will flow into the Northeast, including New England, late next week, around the 16th or a bit afterwards. The issue with New England is that the axis, or center, of the ridge will be centered further west than the huge ridge that was found in the East in late February. This leaves the region vulnerable for backdoor cold fronts,” says Renken.

A backdoor cold front is a cold front that moves from northeast to southwest, instead of the normal northwest to southeast. Thus, the front can be described as “sneaky”, or coming through the “backdoor”, as meteorologically you look for cold front to approach from the northwest. Factors that make New England especially susceptible to backdoor cold fronts are their northern latitude and being near a source of cold air (the chilly north Atlantic Ocean and southeastern Canada). Early spring is the prime season for backdoor cold fronts in New England.

Renken describes when he expects such backdoor fronts to arrive. “The threat for backdoor cold fronts for New England first appears around the 18th. The good news for warm weather fans is that the airmass behind this backdoor cold front shouldn’t be that cold nor will it stick around for long. By the 26th of the month, the threat for any lingering chill will be over and warm west to southwest breezes will send temperatures soaring to way above normal readings once again. “

The result in the of this tumultuous weather pattern will be quite the roller coaster for people in the northeastern US. Winter readings dominate after a cold front and associated wave of low pressure develops on it Thursday into Friday of this week. This cold sticks around until about the 14th or as late as the 16th, depending on your longitude (western areas seeing the warm-up first, New England seeing the warm-up last). Backdoor cold fronts look probable for New England and the mid-Atlantic regions a few days (starting around March 18th) after the warmth arrives and will cut short the mild weather. After about 4-7 days where the threat of chilly weather exists, the warm air moves back in and really means business. New England will see this anomalous warmth move in around the 26th while areas to the south and west will see the mild weather sooner than this.

While recent warm weather has led many to believe spring is arriving early, it is becoming more likely than not that a winter storm will bring accumulating snow to portions of the US east coast this weekend.

Details are slowly coming together for a likely east coast snow storm this coming weekend. While the odds of a storm somewhere along the east coast has increased over the last 24 hours, details of where the snow will set-up and where the rain/snow line will be remain sketchy at best. Important atmospheric data will be sampled tomorrow, helping meteorologists and some of the computer forecast guidance they use in forecasting to improve the overall understanding of a fairly complex weather pattern.

Before we get to the “main event” on Sunday, we need to deal with a fast-moving, weaker system later Thursday and Friday. A weak low pressure system originating in Canada, commonly referred to as a “clipper system”, will approach the Mid Atlantic Thursday night and exit the northeast on Friday. This system will have limited cold air and moisture to work with; as a result, precipitation will be light, and for many it’ll be in liquid form. North of I-195 and south of I-80 in New Jersey, west through Pennsylvania between I-80 and I-276/76, an inch or two of snow may fall by Friday evening, with upwards of 3″ possible in the higher terrain of central Pennsylvania. South of this area, mainly light rain is possible which could end briefly as a period of wet snow with little to no accumulations.

More importantly, this clipper system will help usher in a significantly colder air mass into the eastern US to close out the week and chill down the weekend.

Cold high pressure looks to be in place on Saturday with highs generally 10-15 degrees below normal across much of the Northeast and Mid Atlantic. The potency of this cold high pressure system and the general atmospheric flow across the continent will help determine what exactly happens on Sunday with the potential east coast snow storm.

A few days ago, the European ECMWF forecast model was calling for an all-out blizzard for portions of the eastern United States –a solution we quickly discounted. But it along with other guidance, such as the American GFS forecast model, has come around with more reasonable solutions. While not a blizzard by any means, a significant snowfall is very possible.

There are two possible scenarios for this Sunday storm.

One possibility is the cold high pressure system moving in on Saturday will help supress Sunday’s storm system to the south. Similar to a scenario that happened in January, this could bring heavy snow to portions of Virginia, especially the Hampton Roads / Virginia Beach region. Snow totals will drastically drop off to the north in this scenario, with Cape May, New Jersey on the northern fringe of accumulating snow. This scenario is supported by the latest overnight guidance from both the European ECMWF and American GFS forecast models.

The other scenario suggests that the cold high pressure system won’t be as strong; this would allow the storm system on Sunday to move closer up the northeast coast. This would shift the axis of heavier precipitation further north, but it would also bring the rain/snow line further north too. If such a scenario were to unfold, Pennsylvania and New Jersey would see the heaviest snow, with accumulating snow reaching north along the I-95 corridor, perhaps as far north as Boston. The rain/snow line would flirt with the Pennsylvania/Maryland border and southern New Jersey, keeping any snow totals in those areas low.

Until more of that atmospheric data is sampled, it is still too early to say which scenario will unfold. It is also too early to say which forecast model is “right” or “wrong”, especially with that data not yet ingested by the models. More data will come in over the next 24-48 hours which will help us improve the weekend forecast.

To recap:

A relatively weak clipper system will bring light precipitation to portions of the northern Mid Atlantic later Thursday into Friday.

This clipper system will help usher in a much colder air mass into the northeast.

Depending how strong that high is and how strong a low will be to its south will be, a snow storm is likely somewhere along the east coast; it is just too soon to say where that accumulating snow will set-up.

Forecast guidance is suggesting now that best chances for the heaviest, accumulating snow will be in southeastern Virginia. But until additional data comes in, such guidance can’t be treated as gospel.

Additional data will be in over the next 24-48 hours, which will help meteorologists solidify the weekend forecast.

The latest American GFS model run suggests a significant winter storm for portions of the Mid Atlantic / Northeast next weekend. Other models, such as the European ECMWF and Canadian CMC also have a winter storm in the eastern US, albeit at different locations. Image: TropicalTidbits.com

Overnight computer model forecast guidance has increased the odds of a potential snowstorm in the eastern United States for next weekend. Suggested in earlier runs of the European ECMWF forecast model, the American GFS and Canadian CMC forecast models now all suggest a significant winter storm will form next weekend along with the latest ECMWF forecast model. The devil is in the details though: while the European and American forecast models have some similarities, they bring different amounts of snow to portions of the Mid Atlantic and Northeast; the Canadian, as an outlier, has the storm system much further south than either the American or European models.

These computer forecast models are one of many tools meteorologists use to forecast the weather, but isn’t the only tool. Meteorologists look at weather patterns, recent events, and general climatology to consider if such modeled output is accurate and/or reasonable.

At this time, a snowy situation for next weekend is favored over one that isn’t snowy. But it is still far too soon to know with certainty how this storm will evolve and who will get what type of precipitation. At this time, the best chance for heaviest snow is between Washington, DC and Philadelphia, PA, including southern New Jersey, Delaware, and northeastern Maryland. It is important to point out that this area –and the forecast overall– will continue to evolve and shift over the coming days.

Important weather data needs to be digested by computer forecast models and deciphered by meteorologists in the coming days. The amount of weather data arriving in about the environment over the eastern Pacific Ocean is very limited at this time; with that limited data, knowing how the atmosphere will set-up or not over the western United States to help facilitate a storm system on the eastern United States is not completely known at this time.

Nevertheless, residents should use the “calm” before the storm to make sure they are ready for additional winter weather threats in the coming days. While February ended on a very warm note and long range guidance suggests March may end up very warm too, cold weather and winter storms are still a very real possibility as we move into the next seven days.

Illustration by the Sacramento office of the National Weather Service illustrates the area around the Oroville Dam that could fail.

Roughly 190,000 have been evacuated below the Lake Oroville Dam in California as an emergency, auxiliary spillway shows signs of failure. With experts at the dam expecting an imminent failure of the spillway area Sunday evening, evacuations were ordered as the output of the dam was increased to 100,000 cubic feet per second to alleviate the surplus of water that exists in the lake.

The increased release appears to have prevented additional water from topping the spillway, but the danger of failure remains. As a result of the ongoing failure risk, evacuation orders remain up for the area near the dam.

“The situation has been stressful,” said Mark Ghilarducci, director of the state Office of Emergency Services. “It’s complex and rapidly changing, so we are doing everything we can to support Butte County and the local authorities to be able to address most of the folks who have been displaced.”

California Governor Jerry Brown released a statement Sunday evening after the evacuation order was issued by local authorities. “I’ve been in close contact with emergency personnel managing the situation in Oroville throughout the weekend, and it’s clear the circumstances are complex and rapidly changing,” Brown said. “I want to thank local and state law enforcement for leading evacuation efforts and doing their part to keep residents safe. The state is directing all necessary personnel and resources to deal with this very serious situation.”

The 7-day outlook from the National Weather Service’s Weather Prediction Center shows more heavy precipitation will be impacting California in the coming days, including the area around the Oroville dam crisis.

While it appears the auxilliary spillway may be stable at the moment, the weather forecast shows more trouble is in store for the state that has been rocked all winter by heavy rain and snow.

The 7-day outlook from the National Weather Service’s Weather Prediction Center shows more heavy precipitation will impact northern California. The liquid equivalent of 6-7″ of rain and snow is forecast to fall which will put incredible strain on the fragile situation around Lake Oroville.

There is currently 40,000 cubic feet of water arriving into the lake each second now and additional storms will lead to an exponential increase in that flow. Levees downstream the dam can handle flows of up to 150,000 cubic feet per second before flooding, but with the spillway of the dam compromised and more water rushing in, it may not be possible to hold back the increased flow from increased precipitation.

The Sacramento Bee spoke with Joe Countryman, a member of the Central Valley Flood Protection Board and a former engineer with the U.S. Army Corps of Engineers for context on the engineering issues in the Oroville Dam crisis. When asked about what a failure of the spillway meant, he told them, “It’s not going to be the main embankment failure, but it’s a failure. If it does happen, there’s nothing saying that the ground is going to stay where it is. That force of water will start tearing that hill apart, and it could eat back into the reservoir and drain the reservoir.”

If such a failure does occur, the cities of Marysville, Oroville, Live Oak, and the Highway 70 corridor are at extreme risk. Countryman warns about the area, “That’s gone. I’ll tell you right now that’s gone. If they lose that 30 feet that’s gone”, suggesting the Highway 70 corridor and surrounding communities would be wiped out by the breach.

The Oroville Dam was built in the 1960s; it is an earthfill embankment dam on the Feather River east of the city of Oroville. At 770 feet high, it is the tallest dam in the US and serves mainly for water supply, hydroelectricity generation and flood control. The dam holds back Lake Oroville, the second largest man-made lake in the state of California.

The latest European (ECMWF) model suggests a significant low pressure system off the northeast coast during the middle of next week, bringing blizzard conditions to some.

A wild weather pattern is setting the stage for two more blizzards in the northeast after another potent low pressure system whipped portions of southeastern New England and Long Island with blizzard conditions.

A system later tonight into tomorrow will slide down from the Canadian side of the Great Lakes into the northeast, triggering light snow shower activity across upstate New York. Some light snow may reach south into northeastern Pennsylvania, the northern third of New Jersey, and even the metro area of New York City including Long Island. While a dusting of snow to an inch is possible on the southern side of this system, 1-3″ is possible further north into New England.

A more robust low pressure system will enter the Mid Atlantic late Saturday into Sunday, bringing rain showers to places like Pennsylvania, New Jersey, and New York. As this system makes it way to the Maine coast on Monday, cold air will wrap around the system as it rapidly intensifies south of Nova Scotia. As it does so, heavy snow will break out in Maine from this system. Snow will be thrown back to central Massachusetts and points north, where several inches of fresh snow is expected to fall. In Maine, though, 12-18″ is possible, with the most expected in eastern coastal Maine and much less in the northernmost part of the state.

With powerful winds from this rapidly intensifying system, blizzard conditions will form in eastern Maine, with strong, potentially damaging wind gusts and near-zero visibility due to heavy falling and blowing snow.

This robust system will be far enough away from New York City and places south, like New Jersey, Pennsylvania, Delaware, and Maryland, to bring any precipitation there.

After this blizzard exits the northeast on Monday, eyes will turn to yet another potential storm. Some computer forecast guidance that meteorologists use to aid in their forecasting show another strong low pressure system along the northeastern coast during the middle of the week. As with the last two systems, this next system could go through explosive strengthening, setting the stage for blizzard conditions somewhere in the northeast again.

Next week’s mid-week storm could bring another round of heavy snow whipped up by powerful winds. The best chance of snow will be in areas that saw snow from yesterday’s storm and will see snow from Monday’s storm; odds for snow are low at this time for places south of New York City and northeastern Pennsylvania, although that could change as the stormy weather pattern evolves over the next few days.

The Thursday Snowstorm is expected to drop 6-12″ over a large part of the northeast; snow will fall as far south as southern New Jersey and northern parts of Virginia, Maryland, and Delaware.

A very mild Wednesday is about to be followed by a significant snowstorm on Thursday in the northeastern United States, providing millions with a true meteorological roller coaster experience. A wide area of 6-12″ is expected even though temperatures are forecast to surge into the 50s and 60s across the northeast. As an example, in Philadelphia, we expect a new record high temperature to be made on Wednesday followed by several inches of snow on Thursday.

Low pressure near Chicago this morning anchors a warm front that extends east towards the Mid Atlantic. Tomorrow, this low pressure system will move northeast into Quebec, Canada , drawing the warm front north into the northeastern United States. This warm front will help push a very mild air mass rather far up the east coast, setting the state for high temperature records to be shattered in parts of Pennsylvania, New Jersey, Maryland, and Virginia. This same warm front will push rain, freezing rain, and snow into New England; the rain/snow line from this initial low will actually push into Canada north of the US/Canada border.

As that low pressure system continues its march north and east into Canada, a cold front behind the system will help bring much colder air into the northeast and Mid Atlantic. On Wednesday, a new area of low pressure will develop along this cold front over southern Virginia during the evening hours, intensifying as it heads off the Mid Atlantic coast as Thursday approaches.

On Thursday, this low pressure system is forecast to have just the right ingredients and atmospheric support to develop a robust snowstorm for portions of the northeast. Places getting rain Wednesday afternoon and evening in Pennsylvania and New Jersey will see a transition to plain snow on Thursday morning; some snow could become heavy at times, especially between 6am and 1pm along the I-95 corridor between Philadelphia and New York City and between 1pm and 6pm between New York City and Boston.

Unlike the last significant snow event in January that brought heavy snow to southern New Jersey, the DelMarVa Peninsula, and the Norfolk/Virginia Beach area, snow from this system will be farther north. We expect little to no snow accumulation for Cape May County in New Jersey, the southern two-thirds of Delaware, and much of eastern Maryland. Northern Virginia will be brushed by light snow as will the higher terrain of West Virginia and the mountains of western North Carolina. We expect an inch or two to fall in the northern suburbs of Washington, DC and Baltimore, MD.

Heavier snow is expected across central New Jersey into much of southeastern Pennsylvania and along the Maryland/Pennsylvania border. This area of 3-6″ of snow will stretch back into central Pennsylvania, the mountains of central West Virginia, and into upstate New York east of Route 209 and along I-87 and all points east. We expect 3-6″ to fall in Philadelphia, with lower amounts near the international airport and greater amounts near King of Prussia and points north and west.

The heaviest snow will fall over portions of central Pennsylvania, New Jersey along and north of I-195, the New York City metro area, Long Island, almost all of Connecticut, Rhode Island, and Massachusetts (except for the Cape and nearby Islands where less is expected), southern New Hampshire and Vermont, and southeastern Maine. For New Brunswick, Woodbridge, Newark, Warren, and Summit in New Jersey, we expect amounts in the 6-10″ range; for Manhattan, Staten Island, Long Island and New York City airports, we expect 6-9″; for Stamford, Hartford, Providence, and Boston, we expect 6-10″.

High pressure will build back into the region by Friday, with another warm-up expected over the weekend.

Zone in purple could see accumulating snow on Thursday even after unusual warmth on Wednesday.

Odds are increasing for a Thursday snow threat for portions of the Mid Atlantic and Northeast. Six inches or more of snow may accumulate as ingredients come together for a snowstorm; however, big questions remain about those ingredients and where exactly they’ll come together.

An area of low pressure will track through the Great Lakes region, bringing rain and mild air far up the northeast US coast during the day on Tuesday. Rain will make it as far north as Quebec, Canada. Some freezing rain and snow is also possible across portions of New England, creating slick conditions there later Tuesday into Wednesday. Temperatures are forecast to be very mild if not outright warm over portions of the southern Mid Atlantic as a strong southerly flow sets-up ahead of this low pressure system.

As this low pressure system departs the United States to eastern Canada, significantly colder air will flow down into the Mid Atlantic and Northeast from central Canada. This key ingredient -cold air- will help set the stage for a winter storm on Thursday even after unusual warmth on Wednesday.

A new area of low pressure will form at the surface near the Appalachian Mountains and move east, bringing precipitation to the Mid Atlantic and the Northeast. As this precipitation moves into the cold air, snow will form.

Many storms in recent weeks have quickly departed the eastern US, not getting much time to intensify or put down much in the way of precipitation. However, unlike those previous storms, a bit of an atmospheric “traffic jam” is setting-up over the Atlantic Ocean which will help slow down this Thursday winter storm threat. While there is no complete blocking pattern, the pattern will help slow things down just enough to make the weather interesting.

While interesting, the unfolding weather scenario is very complex with many details yet to be ironed out. While a storm is likely, where it goes, how much cold air it’ll tap into, and how long it will linger remain open questions.

Our map above depicts an area that -could- see snow from Thursday’s storm. Storm track and the rain/snow line will play a major role in who see’s heavy snow or any snow. At this time, it appears the best chance of accumulating snow is over central New Jersey and the New York City metropolitan area. South of there, the rain/snow line may creep north just far enough to keep snow away or snow totals low. Further north and west of the New York City area, if this storm hugs the coast or heads further east than east north east, little to no snow may fall there with most precipitation confined to the coast. The exact storm track will also determine whether southeastern New England sees snow from this storm; the more east-north-east the storm moves rather than north-east, the more likely snow will remain closer to the New York City metro area and not expand north towards Boston. If the system does jog north and east more than expected, significant snow would slide into much of southeastern New England.

More atmospheric readings are needed over the next 24 hours to help forecasters determine who will get precipitation and what form that precipitation will fall in. Until the forecast is refined, those in the purple zone should prepare for the possibility of wintry conditions on Thursday.

Reported snow totals for the event ending January 8, 2017. Source: National Weather Service

The Blizzard of 2017 has wrapped up, blanketing a large part of the eastern US with fairly deep snow. As a matter of fact, there is snow cover reported in every state in the United States except for Florida.

The storm responsible for the significant snow and blizzard conditions in places like Virginia Beach and Cape Cod was the second punch in a 2-punch system that brought wintry precipitation and cold air to the east coast over the last few days.

As this map shows, the heaviest snow fell over central and northern North Carolina, southern Virginia, southeastern Maryland, portions of the Jersey Shore, eastern Long Island, and extreme southeastern New England south of Boston.

While heavy snow fell in many areas, locations away from the coast such as northeastern Pennsylvania, upstate New York (outside of Lake Effect snow areas), and northern Vermont and New Hampshire saw only a dusting to an inch.

That light snowfall is in deep contrast to the heavy snow reported in places like 13.5″ in Ocean View, DE, 12″ in Warren, NC, 9.8″ in Old Bethpage, NY, and 17″ in Plymouth, MA.

A significant winter storm will continue to impact the eastern US over the next 36 hours, dumping exceptionally heavy snow in areas not accustomed to it.

We expect 12-18″ in the Virginia Beach area along with strong winds that will produce blizzard conditions at times.

We also expect snow to accumulate into northern Georgia, Alabama, and portions of Mississippi; snow is also likely across northern South Carolina.

We have increased snow totals somewhat on the northern fringe of this storm. We now expect 3-6″ up against the New Jersey Turnpike in NJ and the NYC metro area; accumulating snow will also spread a bit inland in southeastern New England, with heavier snow expected on the south Jersey shore, eastern Long Island, and extreme southeastern New England. Near Cape Cod, over a foot of snow is possible.

The 4-8 day forecast for Alaska from NOAA’s Weather Prediction Center shows an extended period of south to southwest flow that may lead to an extended mild stretch of weather for much of the Eastern US.

Before Christmas, some meteorologists were busy keeping an eye on the weather near the Bering Sea to understand that the weather would be a few weeks later on the US east coast. (A discussion of the Bering Sea Rule from December 21 can be found here.) On December 21st a pattern change accompanied by a pair of storms about 17-21 days in the future was advertised because of what was going on in the Bering Sea at that time. That pattern change and storms accompanying it can now be clearly seen in the short range forecast.

At the end of December 2016,, much of the eastern two-thirds of the US was at or a bit above normal in terms of temperature. This weather pattern was foretold by the Bering Sea Rule (BSR for short) in the few weeks before December 21 as an area of high pressure had been in control over the sea southwest of Alaska. This particular area of high pressure teleconnected to an area of high pressure over the Deep South that allowed mild, Pacific air to be in control across much of the East and Central US over the last 2 weeks or so.

Now a pattern change and a pair of storms is being seen right at the time the BSR said it would occur. According to Joseph Renken, who has authored papers on the BSR, “The first storm that will travel across the Deep South this weekend and the second on its heels for early next week were foretold by the BSR. Even the fact that the second storm would be slightly further north could of been predicted by what was going in the Bering Sea in mid to late December.”

There is plenty of attention being played to these pair of storms over the next week or so in the meteorological community. But Renken is already looking past these storms into mid-January and beyond, “Look for another repeat of the holiday week weather pattern in mid-January as a broad, long-lived period of south to southwest flow across the East may result starting mid to late next week and potentially lasting for ten days or so, through or beyond the twenty second.” Renken added, “This pattern that will setup is remarkably similar to what happened around the holidays. No record-breaking warmth is likely but no Arctic shots will threaten either . With the cold air being dumped over the West, any chill trying to get East will be greatly modified by the relatively mild land of the Lower Forty Eight.”

So while much deserved brainpower and effort is on these pair of storms that may bring wintry weather to the South and East over the next week, there are experts in the field that are already looking at what may follow. Fans of wintry weather across the East and the South may be disappointed right in the climatological heart of winter.